Electroless copper plating plays an important role in surface treatment, and is mainly applied to a bottom layer in the electroplating of non-metallic materials, metallization of the holes of the printed circuit board, electromagnetic shielding layer of the electronic devices, and etc.
Electroless copper plating now generally uses hydroxyl-containing organic amine as complexants, but such complexants have strong antioxidation, bringing about great difficulty in treating the electroless copper plating wastewater. The copper ions in the wastewater can be removed with a heavy metal trapping agent according to a conventional chemical treatment method, but there is no suitable method to remove the complexants, and due to the presence of the complexants in the wastewater, COD cannot meet the requirements of Emission Standard for Pollutants in Electroplating.
Electroless copper plating often used a salt of carboxyl-containing organic acid as a complexant in the past, such as disodium ethylenediaminetetraacetate and sodium potassium tartrate. However, disodium ethylenediaminetetraacetate has a strong antioxidation and the conventional oxidation method cannot be used to destroy the complexant. Therefore, there are great difficulties in treating the electroless copper plating wastewater that contains such complexant and the treatment results often fail to meet the requirements of Emission Standard for Pollutants in Electroplating.